Alpha iron oxide-alkali metal pyroantimoniate catalyst and process of preparation



Patented Mar. 22, 1949 2,465,313 ALPHA IRON OXIDE-ALKALI METAL PYRO- ANTIMONIATE OF PREPARATION Max A. Mosesman,

CATALYST AND PROCESS Baytown, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N.

of Delaware J a corporation No Drawing. Original application December20,

1946, Serial No. 71758 plication June The present invention is directedto a method for preparing a composition adapted to be used as acatalyst.

This application is a division of Serial No. 717,584, filed December 20,1946, now U. S. Patent No. 2,454,398.

It is known to the art to pass a mixture of carbon monoxide and hydrogenat elevated temperatures and pressures over acatalyst to obtainhydrocarbons and oxygenated derivatives of hydrocarbons as product. Whencarrying out such reactions it is preferred to employ a temperature inthe range of 450 to 675 F. and a pressure in the range of 100 to 500lbs/sq. in.

such processes of reacting hydrogen and carbon monoxide to obtainhydrocarbon product are usually designated as a Fischer-Tropschsynthesis. Heretofore when conducting'such reactions it has beencustomary to employ oxides of such metals as iron, cobalt and nickel asa catalyst; the oxides may be used alone but preferably are used assupported catalysts which are formed by impregnating aluminum oxide,kieselguhr,'or similar carriers with one or more of the desired oxides.

It is an object of the present invention to devise a method forpreparing a catalyst. More particularly, it is an object of the presentinvention to devise a method for preparing a catalyst particularlyadapted for use in the Fischer- Tropsch synthesis. 7

The present invention may be described briefly as involving thepreparation of a mixture of iron oxide and an alkali metalpyroantimoniate, heating the mixture to a high temperature in thepresence of an oxidizing atmosphere for a sufflcient time to oxidizesubstantially the mass, and then contacting the oxidized mass with areducing atmosphere at super-atmospheric temperature to obtain an activemetallic mass.

The alkali metal pyroantimoniate employed in preparing the catalyst inthe persent invention is preferably potassium pyroantimoniate. However,the sodium or lithium pyroantimoniates may suitably be employed undersome conditions. In preparing the catalyst it is preferred to use thealkali metal pyroantimoniate in an amount between 0.2 and 20% of thecatalyst mass and the iron oxide in an amount between 80 and 99.8% ofthe catalyst mass.

The iron oxide component employed in preparing the catalyst may suitablybe ferro-ferric oxide or it may be alpha or gamma iron oxide. Either oneof the three forms may be employed in obtaining good yields ofhydrocarbons and oxy- 4. Divided and this ap- 9, 1948, Serial No. 32,055

11 Claims. (Cl. 252-474) genated compounds in the synthesis ofhydrocarbons from carbon monoxide and hydrogen.

In describing the method for preparing the catalyst mass, reference ismade to employment I of potassium pyroantimoniate. It is to beunderstood that the description is given for illustrative purpose only.In antimoniate, 100 parts of potassium hydroxide are heated in asuitable container until the mass is fused. To the fused molten mass isadded gradu-.

- ally 12.6 parts of 813205, following which the mixture is heated forapproximately 15 minutes and allowed to cool. The cooled reactionmixture has added to it approximately 200 parts of distilled water andis then thoroughly agitated and filtered. The filtrate is set asidewhile the residue has added to it 100 parts or .iolten potassiumhydroxide. Additional amounts of potassium hydroxide to the extent ofparts are then added mixing, is slurried to a thick, smooth paste.

and the total mixture heated for about 15 minutes, cooled and washedwith 200 parts of distilled water. Following the washing treatment, thereaction body is thoroughly stirred and refiltered. The second filtrateis then combined with the first filtrate which has previously been setaside and the combined filtrates evaporated at a reduced pressure at atemperature of C. until crystallization occurs. The crystals whichseparate are filtered free from liquor and are substantially purepotassium pyroantimoniate (K4Sb201).

The crystalline material is further purified by washing with absolutealcohol until substantially free of alkali. The washed crystals aredried at about 97 C. and then a selected amount is added to a weighedamount of iron oxide such as ferroferric oxide, preferably an amount ofthe purified pyroantimoniate suflicient to give a catalyst compositionof 5% potassium pyroantimoniate and iron oxide, and the resultantmixture, after the addition of suificient alcohol to permit This pasteis then dried at 107 C. to form a solid cake like mass which is groundto pass a 30 mesh material is then heated in a free oxygen-containingatmosphere at 1000 F. for about 4 /2 hours and allowed to cool catalyst.

Preferably,

foregoing manner is employed before the catalyst prepared in the insynthesis of hydrocarbons from carbon monoxide and hydro gen, it shouldbe reduced with a reducing gas such as hydrogen or carbon monoxide at atemperature of approximately 500 preparing the potassium pyroto obtainthe finished to approximately 900 F. When hydrogen is the reducing gas,a temperature of about 700 F. and a hydrogen gas rate of about 1000volumes per volume of catalyst per hour should be employed.

The catalyst prepared in the above described manner is highly active insynthesizing hydrocarbons over an appreciable period of time. For

example; over an 816 hour period when employing a catalyst comprising95% iron oxide and 5% potassium pyroantimoniate at a temperature between550 and 575 F., C4 and heavier hydrocarbons in an amount between 192 and198 cc. per cubic meter of feed gas were obtained. During the sameperiod of operation substantial quantities of water were obtained,varying from 29 to as high as 138 and averaging about 50 cc. per cubicmeter of feed gas. The hydrocarbons produced contained substantialquantities of olefins, alcohols calculated as amyl alcohol, aldehydesand organic acids, while the water contained appreciable quantities ofalcohols calculated as ethyl alcohol, aldehydes and organic acids.

While the invention has been described with reference to the employmentof iron oxide as one component of the catalyst composition, it isintended that iron filings or iron powder may be substituted for theiron oxide. On subjecting the composition to the free oxygen-containingatmosphere, the elemental iron would be converted to the oxide.Similarly, while the reducing gas has been illustrated by the use ofhy-' drogen, it is also possible to employ carbon monoxide as thereducing agent. When employing carbon monoxide in lieu of hydrogen asthe reducing agent, lower temperatures of the order of 500 to 700 F. maybe used.

While examples of temperature and pressure conditions suitable for usein the practice of the present invention have been given to illustratethe advantages of the present invention, it will be obvious to a workerskilled in the art that temperatures and pressures over a substantialrange may be employed and good results obtained. It will also be obviousthat the alkali metal pyroantimoniate admixed with the iron oxide may bepresent over a substantial range and satisfactory results obtained-Accordingly, it is intended to embrace such ranges by the claimsappended hereto.

The nature and objects of the present invention having been fullydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent is:

1. A method for preparing a catalyst adapted for use in aFischer-Tropsch synthesis which includes the steps of preparing amixture of alpha iron oxide in an amount in the range between 80% and99.8% by weight and an alkali metal pyroantimoniate in an amount in therange between 0.2 and 20% by weight, heating said admixture at asuperatmospheric temperature of about 1000 F. in the presence of a freeoxygen-contalning atmosphere, and subsequently contacting the admixturewith a reducing atmosphere at a superatmospheric temperature in therange from 500 to 900 F.

2. A method in accordance with claim 1 in which the alkali metalpyroantimoniate is potassium pyroantimoniate.

3. A method in accordance with claim 1 in which the alkali metalpyroantimoniate is sodium pyroantimoniate.

4. A method in accordance with claim 1 in which the alkali metalpyroantimoniate is lithium pyroantimoniate.

5. A method for producing a catalyst suitable for use in theFischer-Tropsch synthesis comprising the steps of admixing alpha ironoxide with potassium pyroantimoniate and alcohol to form a paste, theproportions of said admixture being adjusted to provide a finishedcatalyst consisting of about 95% by weight of alpha iron oxide and about5% by weight of potassium pyroantimoniate, drying the paste to form asolid cake-like mass, grinding the caked mass andforming it intopellets, subjecting said pellets to a free oxygen-containing atmosphereat a temperature of about 100 F. and subsequently to a reducingatmosphere at an elevated temperature in the range of 500 to 900 F. toobtain the finished catalyst.

6. A method for preparing a catalyst suitable for use in aFischer-Tropsch synthesis which consists of the steps of preparing amixture of alpha iron oxide in an amount in the range between and 99.8%by weight and an alkali metal pyroantimoniate in an amount in the rangebetween 0.2 and 20% by weight, heating said admixture to a temperatureof about 1000 F. for about 4 hours in the presence of a freeoxygen-containing atmosphere and subsequently contacting the admixturewith a reducing atmosphere at a temperature of about 700 F.

7. A composition adapted for use as a catalyst in the production ofhydrocarbons and oxygenated hydrocarbons which consists of alpha ironoxide and an alkali metal pyroantimoniate in intimate admixturetherewith in an amount in the range between 0.2 and 20% by weight ofsaid alpha iron oxide which mixture has been contacted with an oxidizingatmosphere at a temperature of about 1000 F. and then with a reducingatmosphere at a temperature in the range from 500 to 900 F.

8. A composition in accordance with claim 7 in which the alkali metalpyroantimoniate is potassium pyroantimoniate.

9. A composition in accordance with claim 7 in which the alkali metalpyroantimoniate is sodium pyroantimoniate.

10. A composition in accordance with claim 7 in which the alkali metalpyroantimoniate is lithium pyroantimoniate.

11. A composition adapted for use as a catalyst in the production ofhydrocarbons and oxygenated hydrocarbons consisting of an intimatemixture of approximately by weight of alpha iron oxide and approximately5% by weight of potassium pyroantimoniate, which mixture has been heatedin the presence of a free oxygencontaining atmosphere at a temperatureof about 1000 F. and subsequently heated in a reducing atmosphereincluding free hydrogen at a temperature of about 700 F.

MAX A. MOSESMAN.

No references cited.

